Sessility (motility)

Sessility means that something cannot move around on its own, like a plant or a rock. They stay in one place and let things come to them.

Motility means that something can move around on its own, like an animal or a person. They are not stuck in one place and can go where they want to.

So, if you are sessile, you can't move around on your own. But if you have motility, you can move around all by yourself!